In a case where phase matching and the likes are performed, inductors and capacitors are used. As for RF (Radio Frequency) systems such as portable telephone devices and wireless LANs (Local Area Networks), there are demands for smaller-sized, less costly, and higher-performance systems. To meet those demands, electronic components such as integrated passive devices each having passive elements integrated therein are used.
Integrated passive devices each having passive elements built in a multilayer ceramic substrate have been developed by the LTCC (low temperature co-fired ceramic). Also, integrated passive devices each having passive elements formed on a multilayer ceramic substrate have been developed.
Japanese Patent Application Publication Nos. 2007-123468 and 2007-31242 disclose techniques by which a coating layer is formed on a ceramic substrate, and passive elements are formed on the coating layer.
The integrated passive devices each having passive elements formed on a multilayer ceramic substrate have the following problems. In a case where a chip is to be flip-chip mounted on a multilayer ceramic substrate having passive elements formed on its upper face, the chip is to be located higher than the passive elements. Therefore, connecting terminals taller than the passive elements are formed on the multilayer ceramic substrate, and the chip is then flip-chip mounted onto the connecting terminals. However, the multilayer ceramic substrate has penetration electrodes penetrating through each of the ceramic layers of the multilayer ceramic substrate. The upper faces of the penetration electrodes protrude from the surface of the multilayer ceramic substrate. Therefore, when connecting terminals are formed on the multilayer ceramic substrate, the heights of the connecting terminals vary depending on whether the connecting terminals are located above the penetration electrodes or are located in regions other than the regions corresponding to the penetration electrode. In a case where a chip is to be flip-chip mounted onto the connecting terminals on the multilayer ceramic substrate, reducing the difference in height between the connecting terminals (coplanarity) is important. If the coplanarity is poor, the mounted chip comes off, and breaking is caused between the connecting terminals. Therefore, the connecting terminals are formed in regions other than the regions corresponding to the penetration electrode, so that the connecting terminals have the same heights. As a result, it becomes difficult to form small-sized electronic components.